Growth and Characterization of Lead-free Piezoelectric Single Crystals

Abstract

Lead-free piezoelectric materials attract more and more attention owing to the environmental toxicity of lead-containing materials. In this work, we review our first attempts of single crystal grown by the top-seeded solution growth method of BaTiO3 substituted with zirconium and calcium (BCTZ) and (K0.5Na0.5)NbO3 substituted with lithium, tantalum, and antimony (KNLSTN). The growth methodology is optimized in order to reach the best compositions where enhanced properties are expected. Chemical analysis and electrical characterizations are presented for both kinds of crystals. The compositionally-dependent electrical performance is investigated for a better understanding of the relationship between the composition and electrical properties. A cross-over from relaxor to ferroelectric state in BCTZ solid solution is evidenced similar to the one reported in ceramics. In KNLSTN single crystals, we observed a substantial evolution of the orthorhombic-to-tetragonal phase transition under minute composition changes.

Spinodal Decomposition in Lead-free Piezoelectric BaTiO3–CaTiO3–BaZrO3 Crystals

“…BCTZ4 polycrystal displayed a high d33= 496pC.N -1 similar to that of ceramics with close compositions 10,32 . Although piezoelectric coefficients d33 are higher than those previously reported in lead-free BCTZ single crystals 13,39,40 , they remain below the predicted ones 10 and those of other lead-free systems 9,[41][42][43] . This feature is mainly due to the fact that BCTZ polycrystals exhibit averaged properties compared to those of single crystals.…”

“…N -1 as predicted by Liu et al 10 . Recently, we reported 12,13 early growth attempt of BCTZ single crystals in BaTiO3-CaTiO3-BaZrO3 pseudo-ternary solid-solution with various zirconium (Zr) and calcium (Ca) contents where a continuous evolution of their electrical properties from relaxor to pure ferroelectric behavior was highlighted with Ca and Zr contents.…”

“…In the present paper, we focus on single crystal growth by Top-Seeded Solution Growth method of BCTZ following the methodology reported in literature 13…”

Single crystal growth of BaZrO3 from the melt at 2700 °C using optical floating zone technique and growth prospects from BaB2O4 flux at 1350 °C

“…Perovskites with general formula ABO 3 are an important family of multifunctional materials [1] and exhibit a broad variety of outstanding properties, which are widely used in various technological applications such as Solid Oxide Fuel Cells (SOFC) [2,3], steam electrolysis [4], substrates for multiferroic materials [5,6], piezoelectricity [7][8][9][10][11][12][13] or catalysis [14][15][16]. Among different perovskite compounds, barium zirconate BaZrO 3 (BZO) has attracted renewed interests as a high-temperature proton conductor [17], a dielectric material for wireless communication applications [18], a substrate for thin-film growth [19,20] and as an inert crucible for superconductors crystal growth [21].…”

(K,Na)NbO3-based piezoelectric single crystals: Growth methods, properties, and applications

“…In general, the use of a self-flux, i.e., a solvent for which all the ions are the same as those of the solute to be grown, is preferred. This is widely encountered for KNN-based single crystals grown from high-temperature solution (example of solvent: K 2 O) [54,55]. On the other hand, heterogeneous flux, i.e., a solvent for which a part of the ions is different from those of the solute to be grown, can also be used.…”